Nitrogen-doped fullerenes for CO2 capture: a DFT study

Abstract

The structural and electronic properties of several nitrogen-doped fullerenes, C_60−2nN_2n (n = 1–12), have been studied using density functional theory (DFT) at the M06L/6-311+G(d)//M06L/6-31G(d) level. The electronic features studied using a molecular electrostatic potential (MESP) topology analysis revealed that increasing the N-doping leads to a large improvement in the electron density of the carbon cage. As a result, the N-doped fullerenes showed a stronger interaction with CO₂ molecules than C₆₀. Also, the formation of large clusters of CO₂ around the N-doped C₆₀ is modeled which revealed that the interaction energy per CO₂ is better than the interaction of a single CO₂ with the same system. The improved interaction of CO₂ in the cluster is attributed to the positive cooperative interaction arising between the adsorbed CO₂ molecules. The study also examined the MESP features and the CO₂ binding affinity of the anionic modification of the N-doped C₆₀ by attaching a CN⁻ unit on a carbon center. Compared to the N-doped C₆₀, the highly electron-rich anion (C_60−2nN_2nCN)⁻ showed improved affinity to CO₂. The superior electronic features and CO₂ binding energy data of N-fullerenes and N-cyanofullerides suggest that they are potent CO₂ capturing agents.